Steven Moffat regrets not writing a more serious romantic scene between Doctor Who's Amy Pond and the Time Lord.
The showrunner will depart the sci-fi series at Christmas - to be replaced by Chris Chibnall - after seven years and while he admits there are "loads of things" he would change about his time on the show, there is one error which haunts him on a daily basis.
He said: "There's loads of things I'd change.
"I'd change all my mistakes, but that'd be exhausting, so let me just choose one mistake. I'll choose one mistake, because it just rankles me to this day that I got this wrong."
In the scene Steven is referring to, there is some sexual tension between Amy - played by Karen Gillan - and Matt Smith's incarnation of the Time Lord following a battle with the Weeping Angels.
While Amy manages to plant a kiss on the Doctor, the scene is filled with comic moments rather than romance, and the writer believes he blew a big chance to pen a more sincere moment between the two characters.
In a Q&A with BBC America, he added: "There's a scene at the end of a season five episode called 'Flesh and Stone', where Amy comes on to the Doctor.
"It's a very good idea for a scene, it's a very good idea, because she's been through this traumatic experience and she doesn't quite know who or what the Doctor is, and she doesn't quite know what his interest is.
"And there's a brilliant scene to be written there, and I entirely avoided writing it. I played it for laughs, and it was so wrong."